Summer passes with just one heat wave

The monsoon has reduced many of us to puddles for almost a week, so this will come as little solace. But San Diego County is only now experiencing its first major heat wave of the summer, and it comes less than three weeks from the official start of fall.

Air is flowing clockwise around a dome of high pressure over Colorado, directing hot weather and monsoonal moisture into Southern California, where thunderstorms exploded like fire crackers on Tuesday afternoon near Julian. Temperatures hit the low 80s in San Diego, where the average high is 77, and the upper 90s inland. It'll be even hotter on Wednesday and Thursday, says the National Weather Service. Escondido might hit 100 degrees.

"It was so cool in early August people were saying it felt as if fall was in the air," said Mark Moede, a weather service forecaster. "We've had a complete change of weather. We've gone from a 'non-soon' to a full-fledged monsoon."

The average temperature at Lindbergh Field, the official weather station for San Diego, was below normal almost 50 percent of the time in June, July and August. The air got especially chilly during a month-long period that began on July 19th. It was reminiscent of the summer of 2010, when some people went sweater shopping before heading to the beach.

Forecasters say the average temperature at Lindbergh was below normal on 43 of 91 days in June, July and August, or 47.2 percent of the time. Such figures are determined by computing the average of each day's highest and lowest temperatures.

"You can directly tie the cooler temperatures at the coast to the weather pattern we had for most of the summer," said Phil Gonsalves, a National Weather Service forecaster. "The high pressure didn't seem to move west of Arizona. So our weather was dominated by low pressure along the West Coast, which caused cool air to circulate ashore, creating a marine layer."

September got off to a warm start at Tamarack with temperatures in the mid-70s. Gary Robbins